基于扩散偶浓度分布模型的薄壁铜(管头)-铝(管路)-铜(接头)组合制冷管路异质金属联接技术工程研究

在中国国家自然科学基金项目《金属间化合物/陶瓷复合材料界面设计及关键制备工艺》资助下，以大幅降低制冷器铜管使用为目的，提出铜(管头) 铝(管路) 铜(管头)组合制冷管路结构，核心科学问题是Cu Al异质金属的密封焊接，提出总结性科学研究报告。 以表征异种金属材料焊接扩散规律为目的，探索基于菲克扩散定理的插入式Cu Al热连接模型。认为原子向空穴迁移或在节点间的迁移是固态金属和合金中的基本扩散运动，在溶剂晶格中溶质原子异扩散(AD)具有方向性，导致溶质原子浓度有局部变化。金属在加热或冷却过程中的相变和组织变化总是与扩散过程(DP)密切相关。固态压焊(SSPW)时，DP是确定再结晶(Recrystallization)和激活面(Surface Activation)之间结合后使焊接接头性能改善的主要过程。建立起扩散过程中溶质原子分布的一维扩散模型，由菲克第一定律建立扩散通量与扩散物质浓度和单向扩散距离的关系模型，由菲克第二定律获得扩散物单向扩散浓度模型，通过玻耳兹曼变换(Boltzmann Transform)求解任何时刻的一维浓度分布c(y，t)，建立基于高斯误差函数(GEF)erf(β)的扩散偶浓度分布模型(CDM)和扩散偶浓度分布曲线(CDC)。基于CDM，建立CDC、扩散系数、原始接触面(OCS) 浓度、理论均匀化判别等工程应用层面的Cu Al焊接扩散模型。

Study on Engineering of Heterogeneous metal Connection Technology for Thin walled Cu (pipe end) Al (pipe) Cu (pipe joint) Combined Refrigeration Pipeline Based on the Concentration Distribution Model of Diffusion Couples

With the purpose of greatly decreasing the usage amount of Cu pipes in refrigerators, and under the support of the National Nature Science Fund Project of “Interface Design and Key Preparation Process for Intermetallic Compounds/ Ceramic Composite Materials”, this paper proposes a Cu (pipe end) Al (pipe) Cu (pipe joint) combined refrigeration pipeline structure. The key problems are to study the seal welding of Cu Al heterogeneous metal, and to present a summarized science research report. This work is to characterize the diffusion rule of welding of heterogeneous metals, and quest for a plug in Cu Al thermal connection model based on the Fick’s Diffusion Law.the oxide layers on the surface of Al pipe when the taper side of Cu pipe with higher hardness is pressed into the Al pipe, resulting in the clean welding surface. On the other hand, since the Cu/Al welding joint can grow into Cu/Al eutectic structure in the range of 363 1048℃ and the heating is unavoidable, 5 mm welding line without low melting morphology can be formed when the Cu/Al joint is extruded out of the welding line under the axial, radial and flaring pressure, which can realize the diffusion connection between Cu and Al atoms. Thus, the Electric Resistance Pressure Composite Welding (RPCW) process flow, a method to prepare Cu Al welding line without eutectic structure and welding fixtures are developed by integrating Cold Pressure Welding (CW) and Electric Resistance Welding (RW). Observed by the 1000 times metallographic microscope, there are no low melting point materials between welding lines of Cu/Al fusion region in the range of 5 mm near to welding line on the outer surface.